Entanglement swapping of two arbitrarily degraded entangled states

Kirby, Brian T.; Santra, Siddhartha; Malinovsky, Vladimir S.; Brodsky, Michael

doi:10.1103/physreva.94.012336

Cited by 38 publications

(24 citation statements)

References 34 publications

(57 reference statements)

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“…The density matrix for the teleported 2-photon state of XX E and X L is then obtained by tracing out X E and X L from the 4-photon density matrix [102]:…”

Section: Entanglement Teleportation With Real Emittersmentioning

confidence: 99%

Entanglement teleportation with photons from quantum dots: towards a solid-state based quantum network

Rota

Basset

Tedeschi

et al. 2020

IEEE J. Select. Topics Quantum Electron.

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Semiconductor quantum dots are currently emerging as one of the most promising sources of non-classical light on which to base future quantum networks. They can generate single photons as well as pairs of entangled photons with unprecedented brightness, indistinguishability, and degree of entanglement. These features have very recently opened up the possibility to perform advanced quantum optics protocols that were previously inaccessible to single quantum emitters. In this work, we report on two experiments that use the non-local properties of entanglement to teleport quantum states: three-photon state teleportation and four-photon entanglement teleportation. We discuss all the experimental results in light of a theoretical model that we develop to account for the nonidealities of the quantum source. The excellent agreement between theory and experiment enables a deep understanding of how each parameter of the source affects the teleportation fidelities and it pinpoints the requirements needed to overcome the classical limits. Finally, our model suggests how to further improve quantum-dot entangled-photon sources for practical quantum networks.

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“…The density matrix for the teleported 2-photon state of XX E and X L is then obtained by tracing out X E and X L from the 4-photon density matrix [102]:…”

Section: Entanglement Teleportation With Real Emittersmentioning

confidence: 99%

Entanglement teleportation with photons from quantum dots: towards a solid-state based quantum network

Rota

Basset

Tedeschi

et al. 2020

IEEE J. Select. Topics Quantum Electron.

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“…Photons from modules at neighboring repeater stations interfere at a beam splitter between the repeater stations. The coincident detection of two photons at the two outputs of the beam splitter then projects the state of the Ba + ions into an entangled state with a success probability of 1 2 [43]. The success probability of generating entanglement between two Ba + ions located at neighboring stations in one trial is, p e c L L 1 2 2 0 a t t h = -, where L 0 is the spacing between neighboring repeater stations and η c is the coupling efficiency including emission, collection and coupling loses.…”

Section: Architectures For Quantum Repeatersmentioning

confidence: 99%

“…where L att =20 km for conventional optical fibers. The factor of 1 2 occurs because of linear optical Bell state measurement [43]. Photon loss errors reduce the rate of obtaining remote entangled states and result in lower raw key generation rates.…”

Section: Error Modelmentioning

confidence: 99%

Quantum repeaters based on two species trapped ions

et al. 2019

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We examine the viability of quantum repeaters based on two-species trapped ion modules for longdistance quantum key distribution. Repeater nodes comprised of ion-trap modules of co-trapped ions of distinct species are considered. The species used for communication qubits has excellent optical properties while the other longer lived species serves as a memory qubit in the modules. Each module interacts with the network only via single photons emitted by the communication ions. Coherent Coulomb interaction between ions is utilized to transfer quantum information between the communication and memory ions and to achieve entanglement swapping between two memory ions. We describe simple modular quantum repeater architectures realizable with the ion-trap modules and numerically study the dependence of the quantum key distribution rate on various experimental parameters, including coupling efficiency, gate infidelity, operation time and length of the elementary links. Our analysis suggests crucial improvements necessary in a physical implementation for cotrapped two-species ions to be a competitive platform in long-distance quantum communication. efficiently entangled to photons and a different longer lived species of ions ( 9 Be + or 171 Yb + ) that can be utilized as a quantum memory qubit and for local processing. A high-fidelity transfer of quantum information between the two species of ions can also be achieved [29]. Furthermore, due to transition-frequency difference the optical operations with the communication ions do not disturb the quantum memory ions even though they are only a few microns away. Despite such experimental advances an analysis of quantum key generation rates, among the most promising uses of a quantum network, using TSTI for quantum repeaters is lacking.We describe in this paper a quantum repeater architecture based on modules of two species of trapped ions. We study the viability of using these modules as building blocks for the construction of long-distance quantum repeaters by analyzing quantum key distribution rates. The architecture can potentially work for any pair of communication and memory ions. For the numerical results later in the paper, however, we consider the advances made with the 171 Yb + -138 Ba + pair described in [41] with the following features: excellent isolation between 171 Yb + quantum memory ions and 138 Ba + communication ions was achieved and a state transfer between them was demonstrated; Ba + coherence times of 100 μs in unstabilized magnetic fields and a coherence time of 4 ms with stabilized magnetic fields were measured; same-species two-qubit gates between 171 Yb + ions with 98% fidelity and cross-species two-qubit gates between a 171 Yb + ion and 138 Ba + ion with 75% fidelty in 200 μs were demonstrated; light collection efficiency from the 138 Ba + ion of about 10% and fiber coupling efficiency of 17% in the absence of a cavity were reported. Our analysis suggests crucial improvements in the performance parameters that can maximize key generation rates. We foc...

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“…This behavior, where entanglement threshold value is required for exploiting the quantum nature of the involved systems and the nonlocal effect of quantum correlation, is also present in the scheme for entanglement 310 swapping [61,63], in the protocol for Bell inequality violations, and therefore in secure quantum cryptography [25,29].…”

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confidence: 94%

Entanglement thresholds for displaying the quantum nature of teleportation

et al. 2016

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A protocol for transferring an unknown single qubit state evidences quantum features when the average fidelity of the outcomes is, in principle, greater than 2/3. We propose to use the probabilistic and unambiguous state extraction scheme as a mechanism to redistribute the fidelity in the outcome of the standard teleportation when the process is performed with an X−state as a noisy quantum channel. We show that the entanglement of the channel is necessary but not sufficient in order for the average fidelity f X to display quantum features, i.e., we find a threshold C X for the concurrence of the channel. On the other hand, if the mechanism for redistributing fidelity is successfully then we find a filtrable outcome with average fidelity f X,0 that can be greater than f X .In addition, we find the threshold concurrence of the channel C X,0 in order for the average fidelity f X,0 to display quantum features and surprisingly, the threshold concurrence C X,0 can be less than C X . Even more, we find some special cases for which the threshold values become zero.

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Entanglement swapping of two arbitrarily degraded entangled states

Cited by 38 publications

References 34 publications

Entanglement teleportation with photons from quantum dots: towards a solid-state based quantum network

Entanglement teleportation with photons from quantum dots: towards a solid-state based quantum network

Quantum repeaters based on two species trapped ions

Entanglement thresholds for displaying the quantum nature of teleportation

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